Single-vane rotary pump or motor

ABSTRACT

A rotary vane pump or motor comprising a housing ( 16 ) with cylindrical inner peripheral wall defining a cavity, and a rotor ( 20 ) with cylindrical peripheral surface and a socket ( 41 ) internal to said peripheral surface, eccentrically disposed in the cavity. The rotor ( 20 ) is adapted to scroll the inner peripheral wall in close proximity thereto. The inner peripheral wall and the rotor surface define a working chamber between them. The housing ( 16 ) has a vane ( 22 ) with an end received within the socket ( 41 ) so as to enable the vane to slide in the socket maintaining predetermined degree of fluid tightness therebetween, and to enable the rotor ( 20 ) to orbit the cavity. The housing ( 16 ) has an inlet port ( 24 ) adjacent one side of the vane and an outlet port ( 26 ) adjacent the other side of the vane, both ports being open to the inner peripheral wall.

FIELD OF THE INVENTION

The present invention relates generally to vane pumps and motors andmore particularly, to single-vane rotary pumps used for pumping offluids in the chemical, medical and food industries, where the requiredprocess cleanliness necessitates frequent pump cleaning or replacement.

BACKGROUND OF THE INVENTION

The single vane rotary pump/motor is known historically from attempts tobuild a steam engine with a rotary piston. Later the scheme was appliedto compressors/pumps. (It is known in the art that, generally, a rotarypiston engine (motor) is convertible into a pump if an external drive isprovided, and vice-versa.) Thus, GB 926,495 discloses a rotary pumpwhere the general layout includes a housing with a cylindrical cavityand a cylindrical piston (rotor) of lesser diameter eccentricallydisposed therein. The pump drive, by means of an eccentric crank, causesthe piston to orbit the cavity scrolling its inner peripheral wall. Apump chamber with crescent shape is thus defined between the piston andthe housing. The piston has a radial projection (vane) accommodated in arecess of the housing, which divides the chamber into an expandingchamber and a contracting chamber. The pump further has an inlet port atone side of the vane, connected to the expanding chamber, and an outletport at the other side of the vane, connected to the contractingchamber. In one embodiment, the vane has a cylindrical tip, while therecess is a radial channel with parallel walls contacting thecylindrical tip and allowing the vane to slide and swivel. In anotherembodiment, the vane and the recess have triangular shape.

A few examples of single-vane pumps are provided in Japanese publicationJP 06-200887. The pump has a single vane connected to the rotor and tothe housing across the pump chamber. In one embodiment, the vane isslidably engaged to the housing while hinged to the rotor. In a secondembodiment, the vane is also slidably engaged to the housing—however,the vane is not joined to the rotor but is radially urged to the rotorby a spring in the sliding joint so that the vane is in sliding contactwith the rotor. In a third embodiment, the vane is integral with therotor, while sliding through a socket which in its turn is rotatablyjoined to the housing.

In most embodiments, the outlet port is closed by a one-way check valveto prevent backflow of fluid, or pressure loss, when the scrolling zoneof the rotor passes over the vane joint, since neither the vane, nor therotor in that position isolate the inlet port from the outlet port ofthe pump.

SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided a rotaryvane pump or motor comprising a housing with cylindrical innerperipheral wall defining a cavity, and a rotor with cylindricalperipheral surface and a socket internal to said peripheral surface,eccentrically disposed in the cavity. The rotor is adapted to scroll theinner peripheral wall in close proximity thereto. The inner peripheralwall and the rotor surface define a working chamber between them. Thehousing has a vane with an end received within the socket so as toenable the vane to slide in the socket maintaining predetermined degreeof fluid tightness therebetween, and to enable the rotor to orbit thecavity. The housing has an inlet port adjacent one side of the vane andan outlet port adjacent the other side of the vane, both ports beingopen to the inner peripheral wall. The scroll zone of close proximitybetween the rotor surface and the inner peripheral wall of the housing,and the vane divide the working chamber into a first expanding inletchamber in fluid communication with the inlet port and a secondcontracting outlet chamber in fluid communication with the outlet port.

In one embodiment, the socket has parallel walls and the vane has acylindrical tip received in the socket and providing fluid tightnesstogether with the walls. The vane is rigidly attached to the housing butis thinner than its cylindrical tip, thus allowing for rocking motionwithin the socket.

In another embodiment, the socket has an opening with two rounded lipsreceiving the vane therebetween and providing therewith the fluidtightness. The socket has a wider cavity behind the lips such that thevane is able to rock in the socket. The vane may have parallel wallsproviding, at variable angles of rocking, variable fluid tightness.Alternatively, the protrusions may be elastic, or vane thickness mayvary along vane length, thereby providing, at variable angles ofrocking, approximately uniform fluid tightness.

In a further embodiment, the socket has an opening formed as a swivelcylindrical joint allowing sliding of the vane, of uniform thickness,through the joint and rocking of the vane together with the joint.

In still further embodiments, the socket has parallel walls and the endof vane received in the socket matches the clearance between theparallel walls, but the vane is not rigidly attached to the housing. Thevane may be attached to said housing by a hinge, or may be madeflexible, so as to bend when the rotor orbits within the housing.Preferably, in the latter case, the parallel walls conjoin theperipheral surface along a smooth curve allowing the vane to bendsmoothly.

The inventive design affords two major advantages. The first is theability to position the pump/motor inlet and outlet in closer proximityto each other, and thus reduce the rotational angle at which the rotorand cylinder are not in scrolling contact. The second advantage is thatthe rotor is balanced when exposed to fluid pressure, as the sealingbetween the vane and the rotor occurs at the rotor periphery. Thus thefluid pressure applies a force directed through the rotor center,resulting in negligible force between the vane and the rotor socket, asopposed to prior art rotors, where the protruding vane is exposed topressure, which urges the vane against its socket, creating friction.(Note: This benefit does not apply to structure shown in FIG. 6). Anadditional advantage of the vane extending inwards from the housing isthe structural compactness obtained with pumps that employ long vanes.

In accordance with an additional embodiment of the present invention,the rotary vane pump or motor comprises a sealing barrier disposedbetween the rotor periphery and the inner peripheral wall, preferablyadjacent to the inlet port or to the outlet port. The barrier is adaptedto prevent fluid communication between the inlet port and the outletport when the scroll zone is over the inlet port or the outlet port orbetween them. Preferably, a second sealing barrier is disposed adjacentto the other port. The sealing barrier may be made of compliant materialand attached to the inner peripheral wall or to the rotor periphery.Alternatively, it may be formed as cooperating teeth on the innerperipheral wall and on the rotor peripheral surface. The sealing barriermay be formed as an integral detail with the lips at the socket opening.Thereby, a single-vane pump or motor is provided, which does not requirecheck-valves to function, but rather employs a barrier, to maintainseparation between the pump or motor inlet and outlet.

In accordance with another aspect of the present invention, the rotaryvane pump is used in a pumping apparatus, coupled to a drive unit withan eccentric drive member adapted to drive the rotor. The pump isattachable to and detachable from the drive unit, the two units beingconstructed so that attaching the pump to the drive unit results inengagement of the rotor to the eccentric drive member. Preferably, thepumping apparatus includes attachment means allowing simple manipulationwithout tools.

Preferably, the rotor has a concentric socket, the eccentric drivemember comprises an eccentric crank adapted to fit rotatably, by abearing, into the concentric socket when the pump is attached to thedrive unit, and the housing has a sealed opening allowing the crank toenter the concentric socket. Preferably, the crank has a tapered headwith such diameter and eccentricity that it can enter the concentricsocket irrespective of the alignment between the socket and the crankbefore the attaching.

The rotary vane pump is preferably made of materials suitable for itsusage as a disposable unit, such as plastic.

Thus, a pumping apparatus constructed of two main components isprovided: a permanent drive unit, which contains all the costlycomponents, and a low-cost disposable pump unit, which comes in contactwith the pumped media, and is easily and quickly replaceable. Thedisposable pump unit contains all the pump parts which are subjected tohigh rate of wear or contamination, such that its replacement results ina complete pumping apparatus which is as good as new with respect towear and cleanliness.

The rotary vane pump of the present invention may further comprise abypass channel, preferably integral with the housing, with an inlet incommunication with the inlet port, an outlet in communication with theoutlet port, and a one-way valve disposed between the inlet and theoutlet so as to allow fluid flow bypassing said pump chamber, therebyimproving flow uniformity, while the rotary vane pump is pulsating whenpumping. The pump may further comprise a pulsation damper with an airchamber, connected to the outlet, adapted for damping the pressureripple present at the rotary vane pump outlet.

Other objects and features of the present invention will become apparentwhen viewed in light of the detailed description of the preferredembodiment when taken in conjunction with the attached drawings andappended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to understand the invention and its application, preferredembodiments will now be described, by way of non-limiting examples only,with reference to the accompanying drawings, in which:

FIG. 1 is a schematic cross sectional view of a single vane pump inaccordance with a preferred embodiment of the present invention, coupledwith a pulsation damper and a by-pass valve;

FIG. 2 is a schematic cross sectional view of the single vane pump ofFIG. 1, with the rotor in registration with the vicinity of the fluidinlet and outlet ports.

FIG. 3 is a cross sectional view of the single vane pump of FIG. 1,showing the attachment and coupling of the pump to the drive unit andthe eccentric drive member;

FIG. 4 is a cross sectional view of the single vane pump of FIG. 3,showing the disassembly and decoupling of the pump from the drive unitand the eccentric drive member;

FIGS. 5 and 6 are cross sectional views of the single-vane pump inaccordance with alternative embodiments of the present invention;

FIG. 7 is a close-up of an embodiment where lips of the socket and asealing barrier are integrated in one detail;

FIG. 8 is an embodiment of the present invention with a hinged vane; and

FIG. 9 is an embodiment of the present invention with a flexible vane.

DETAILED DESCRIPTION OF THE INVENTION

With reference to FIGS. 1 through 4, there is shown a pumping apparatus10 in accordance with a preferred embodiment of the present invention.The pumping apparatus 10 comprises a single vane pump 12 and a driveunit 14 detachably attached to each other.

The pump 12 includes a housing 16 with a cylindrical cavity, and acylindrical rotor 20 disposed eccentrically in the cavity of the housingso as to define a working chamber 18. The housing 16 has an inlet port24 and an outlet port 26 communicating with the working chamber 18, anda radial vane 22 disposed between the ports 24 and 26. Ports 24 and 26are opened at the inner peripheral wall 28 of the working chamber. Thehousing 16 includes a bypass channel 29 with an inlet 30 incommunication with the inlet port 24, an outlet 32 in communication withthe outlet port 26, and a one-way valve 34 between the inlet and theoutlet Two sealing barriers 35 are disposed at the peripheral wall 28,adjacent the inlet port 24; and the outlet port 26, respectively. Thehousing 16 has a central opening 36 at its wall 37 and a cover 38closing the working chamber 18.

The rotor 20 is disposed in the housing cavity in sliding contact withthe cover 38 and the wall 37, sealing the opening 36 by means of a ringseal 40. The rotor 20 has a radial socket 41 with two rounded lips 42 atits opening engaging the vane 22 so that it can slide within radialsocket 41. Lips 42 are at all times in contact with both sides of vane22, in a sealing fit. Vane 22 has varying thickness, for maintainingcontact with both lips 42, yet allowing for free movement of rotor 20.Vane 22 and the socket 41 thus constitute a joint providing both slidingand rocking. Rotor 20 further has a central socket 44 facing the opening36.

Drive unit 14 has a rotary shaft 50 with an eccentric crank 52 equippedwith a bearing 54. When pump 12 is attached to drive unit 14, crank 52is received by central socket 44 and shaft 50 is coaxial with thecylindrical cavity of the housing 16.

The radial geometrical relationship between drive unit 14, eccentriccrank 52, rotor 20 and diameter of the cylinder pump chamber 18 is suchthat rotation of rotary shaft 50, via the crank 52, causes rotor 20 toscroll the inner peripheral wall 28, maintaining contact or near-contactwith the wall at scroll zone 56. Due to the vane-and-socket joint ofrotor 20 to the housing 16, where rotor 20 is confined to vane 22 bymeans of vane socket 41, the rotor performs simultaneously areciprocating motion parallel to the vane socket, and a transverserocking motion (an orbital motion).

During this orbital motion, rotor 20 and housing 16 define two separateand variable volumes: an expanding inlet chamber 58 and a contractingoutlet chamber 60. Expanding chamber 58 is defined between the inletside of the vane 22, a portion of the peripheral wall 28 between theinlet port 24 and the scroll zone 56, and an adjacent portion of therotor's periphery. Contracting chamber 60 is defined between outlet sideof the vane 22, the remaining portion of the peripheral wall 28 betweenthe outlet port 26 and the scroll zone 56, and the remaining portion ofthe rotor's periphery.

When the eccentric crank 52 rotates counterclockwise (see FIG. 1),scroll zone 56 also travels counterclockwise, and expanding chamber 58expands, thereby drawing or suctioning fluid from inlet 30, throughinlet port 24. At the same time, contracting chamber 60 contracts,discharging the fluid through outlet port 26 to outlet 32. In theposition shown in FIG. 2, scroll zone 56 is in registration with vane 22so that contracting chamber 60 has vanished while expanding chamber 58has attained its maximal volume, after which it starts contracting andbecomes the contracting chamber, while at the same time a “new”expanding chamber is born.

In the position of FIG. 2, rotor 20 is in contact with the sealingbarriers 35, thereby sealing off possible communication between inletport 24 and outlet port 26 around rotor 20. Barriers 35 are made ofelastic material, such as rubber, such that they are deflected by rotor20 as it scrolls by them. In the absence of barriers 35, when the rotor20 is in the illustrated position, or rather in any position wherescroll zone 56 is in registration with either inlet port 24 or outletport 26, or between them, pressurized fluid from outlet port 26 couldflow around rotor 20 back to inlet port 24. This undesirable reverseflow is traditionally prevented by use of a one-way valve at the outletport. Sealing barriers 35 perform an equivalent function, preventingfluid back flow from the outlet port 26 to the inlet port 24, withoutthe negative effects, which valves introduce.

Notably, fluid backflow may be prevented also by a single sealingbarrier 35. In such case, the single barrier should provide the sealingof a slightly wider gap. For example, if the left barrier in FIG. 2 isremoved, the remaining right barrier 35 must keep the gap between therotor 20 and the inner wall 28 sealed until the scroll zone 56 reaches apoint to the left of the inlet port 24.

It would be obvious to those skilled in the art that any barrier,suitably disposed between the rotor 20 and the inner peripheral wall 28,may perform the function of blocking off the backflow path from outletport 26 to inlet port 24. For example, the barriers may be disposed onthe rotor periphery opposite ports 24 and 26, as shown in FIG. 5.Alternatively, a labyrinth barrier 43, shown in the close-up of FIG. 2,may be formed as cooperating teeth on the inner peripheral wall and onthe rotor peripheral surface.

The bypass one-way valve 34 is optional. It is made of resilientmaterial, such as rubber, which may deflect under pressure differentialapplied thereto, permitting fluid to flow from inlet 30 to outlet 32.Thus, continuous flow of fluid may be maintained also at the time whenexpanding chamber 58 and contracting chamber 60 are not displacingfluid.

In the illustrated preferred embodiment of FIG. 1, the single vane pump10 is shown assembled with an additional pulsation damper 64 which inthis embodiment is a trapped air reservoir with fluid outlet 66. Damper64 absorbs and dampens pressure ripple or fluctuations resultant fromthe cyclic nature of the fluid displacement in the single vane pump 10.Trapped air 68 expands and contracts in response to pressurefluctuations of the fluid at outlet 32, enhancing, together with by-passvalve 34, stable and uniform flow and pressure of the pumped fluid atoutlet 66.

FIG. 3 illustrates pump 12 of the pumping apparatus 10, attached to thedrive unit 14, with the rotor 20 coupled to eccentric crank 52, viabearing 54. The pump is retained in place by wing nuts 70, which aremanually screwed and tightened on threaded studs 72 anchored in driveunit 14. Drive unit 14 has a protrusion 74 mated to recess 76 in housing16 such that pump 12 is keyed in proper relation to drive unit 14.

FIG. 4 illustrates pump 12 detached from drive unit 14, with wing nuts70 removed from threaded studs 72. Cover 38 may be an integral part ofpump 12 permanently attached to housing 16, or it may be separate fromhousing 16. In the illustrated embodiment, it functions both as a coverfor the housing 16 as well as a retaining plate for retaining pump 12engaged to drive unit 14. It will be appreciated that there are othersimple and fast means for manual attaching the pump to the drive unit,for example, a bayonet lock or a threaded collar.

Eccentric crank 52 has a tapered head 78 facilitating the insertion ofthe crank 52 into the socket 44 of rotor 20. The diameter of taperedhead 78 and eccentricity of the crank 52 are selected so that taperedhead 78 can enter into crank socket 44 while the pump is being attachedto the drive unit, irrespective of the alignment of the socket 44 andcrank 52. For this purpose, the crank eccentricity is preferably lessthan one-fourth of the crank head diameter (the latter is presumed equalto the socket 44 diameter).

The rotary vane pump of the present invention can be easily adapted fordisposable use in the chemical, medical and food industries, where therequired process cleanliness necessitates frequent pump cleaning orreplacement. For this purpose, the pump is made of low-cost materialssuitable for its usage as a disposable unit, such as plastic. Thedescribed structure of the vane-and-socket connection allows simple pumpfabrication from molded components. Thus, the pump parts which come incontact with the pumped media are cheap and easily and quicklyreplaceable by a simple manipulation, without using any tools. Thedisposable pump unit advantageously contains all the pump parts that aresubject to high rate of wear and contamination, while the permanentdrive unit, including the eccentric crank with the bearing, contains allcostly components. Thus, the replacement of the disposable pump unitresults in a complete pumping apparatus which is as good as new withrespect to wear and cleanliness.

The vane-and-socket joint in the pump or motor of the present inventionmay be designed in a number of various ways, as shown in FIGS. 5 and 6.In an alternative embodiment of FIG. 5, the vane 22 is made flat, whilesocket 41 is equipped with swivel jaws 82 forming a swivel joint at theopening of the socket. Swivel jaws 82 form a channel of uniform width,mated to vane 22 so that the vane can slide across the swivel whilerotor 20 orbits.

As shown in FIG. 6, vane 22 may be made with an enlarged cylindrical tip80, while the vane socket 41 has parallel walls allowing sliding of tip80 and rocking of rotor 20.

Although a description of specific embodiments has been presented, it iscontemplated that various changes could be made without deviating fromthe scope of the present invention. For example, vane 22 in theembodiment shown in FIG. 1 may be simplified to have parallel walls if ahigh degree of fluid tightness is not required. Alternatively, lips 42may be made of elastic material. As shown in FIG. 7, the lips may beintegrated in one detail 82 with the sealing barrier. FIGS. 8 and 9 showother possible embodiments of the present invention—vane 84 with hinge86, and flexible vane 88 with rounded socket entrance 90. Such vanes maybe made only to slide in a narrow socket 91, without rocking therein,for better fluid tightness. Accordingly, it is intended that theinvention be limited only in terms of the appended claims.

While the performance of the pump embodiment was described, the sameembodiment will perform the motor function, when fluid pressure isapplied at the inlet port, with lower pressure at the outlet port,applying torque to the rotor, which will result in the rotor's rotation.

1. A rotary vane pump or motor comprising a housing with a cylindrical inner peripheral wall defining a cavity, a rotor with a cylindrical peripheral surface and a socket internal to said peripheral surface, said rotor being disposed eccentrically in said cavity and being adapted to scroll said inner peripheral wall in close proximity thereto, said inner peripheral wall and the rotor peripheral surface defining between them a working chamber, said housing having a vane with an end received in said socket so as to enable said vane to slide within said socket maintaining predetermined fluid tightness therebetween, and to enable said rotor to orbit within said cavity, said housing having an inlet port adjacent to one side of said vane and an outlet port adjacent to the other side of said vane, both ports being in fluid communication with said cavity via said inner peripheral wall.
 2. The rotary vane pump or motor according to claim 1, wherein said socket has parallel walls and the end of said vane received in said socket is cylindrical and matches the clearance between said parallel walls.
 3. The rotary vane pump or motor according to claim 1, wherein said vane is attached to said housing by a hinge.
 4. The rotary vane pump or motor according to claim 1, wherein said vane is flexible so as to bend when said rotor orbits within said housing.
 5. The rotary vane pump or motor according to claim 4, wherein said parallel walls conjoin said peripheral surface along a smooth curve allowing said vane to bend smoothly.
 6. The rotary vane pump or motor according to claim 1, wherein said vane is rigidly attached to said housing.
 7. The rotary vane pump or motor according to claim 6, wherein said socket has parallel walls, said vane has a cylindrical tip received in said socket and providing, in cooperation with said walls, said fluid tightness, said vane being thinner than said tip, such that said vane is able to rock within said socket.
 8. The rotary vane pump or motor according to claim 6, wherein said socket has an opening defined by two lips receiving said vane therebetween and providing therewith said fluid tightness, said socket further having a wider cavity behind said opening such that said vane is able to rock within said socket.
 9. The rotary vane pump or motor according to claim 8, wherein said vane has parallel walls providing, at variable angles of rocking, variable fluid tightness.
 10. The rotary vane pump or motor according to claim 8, wherein said vane has parallel walls while said protrusions are elastic, thereby providing, at variable angles of rocking, approximately uniform fluid tightness.
 11. The rotary vane pump or motor according to claim 8, wherein said vane has variable thickness along its length such that, at variable angles of rocking, approximately uniform fluid tightness is provided.
 12. The rotary vane pump or motor according to claim 6, wherein said socket has an opening with swivel jaws, said vane has uniform thickness, and said vane is received between said jaws so as to form a swivel joint allowing sliding of said vane through said joint and rocking of the vane together with said joint, while maintaining fluid tightness.
 13. The rotary vane pump or motor according to claim 1, further comprising a sealing barrier disposed between said rotor surface and said inner peripheral wall and adapted to prevent fluid communication between said inlet port and said outlet port when said rotor is in scroll registration with said inlet port or said outlet port, or any point therebetween.
 14. The rotary vane pump or motor according to claim 13, wherein said sealing barrier is disposed adjacent to one of said inlet or outlet ports.
 15. The rotary vane pump or motor according to claim 14, wherein a second sealing barrier is disposed adjacent to the other of said inlet or outlet ports.
 16. The rotary vane pump or motor according to claim 13, wherein said sealing barrier is attached to said housing.
 17. The rotary vane pump or motor according to claim 13, wherein said sealing barrier is attached to said rotor.
 18. The rotary vane pump or motor according to claim 13, wherein said sealing barrier is made of elastic material.
 19. The rotary vane pump or motor according to claim 13, wherein said sealing barrier is formed as cooperating teeth on said inner peripheral wall and on said rotor peripheral surface.
 20. A rotary vane pump according to claim 1, further comprising a bypass channel with an inlet in communication with said inlet port, an outlet in communication with said outlet port, and a one-way valve disposed between said inlet and said outlet so as to allow fluid flow from said inlet to said outlet bypassing said pump chamber.
 21. The rotary vane pump according to claim 19, wherein said bypass channel is integral with said housing.
 22. A rotary vane pump according to claim 1, further comprising a pulsation damper connected to said outlet port.
 23. A rotary vane pump according to claim 1, in a pumping apparatus further comprising a drive unit adapted to rotate said rotor by means of an eccentric drive member.
 24. The pump according to claim 23, wherein said pump is attachable to and detachable from said drive unit.
 25. The pump according to claim 24, wherein said pump and said drive unit are constructed so that attaching said pump to said drive unit results in engagement of the rotor to the eccentric drive member.
 26. The pump according to claim 25, including attachment means allowing for said attaching by simple manipulation without tools.
 27. The pump according to claim 25, wherein said rotor has a concentric socket, said eccentric drive member comprises an eccentric crank adapted to fit rotatably into said concentric socket when said pump unit is attached to said drive unit thereby providing said engagement, and said housing has an opening allowing said crank to enter said concentric socket.
 28. The pump according to claim 27, wherein said crank comprises a bearing permanently affixed thereto, said bearing providing the rotatable fit of said crank to said concentric socket.
 29. The pump according to claim 28, wherein said crank has a tapered head and has such diameter and eccentricity that said tapered head can enter said concentric socket during said attaching irrespective of the alignment between said concentric socket and said crank before said attaching.
 30. The pump according to claim 24, wherein said pump is made of materials suitable for its usage as a disposable unit.
 31. The rotary vane pump or motor according to claim 17, wherein said socket has an opening defined by two lips receiving said vane therebetween, said socket further having a wider cavity behind said opening such that said vane is able to rock within said socket, said lips being made of elastic material formed so as to provide said fluid tightness between the vane and the socket and to constitute said sealing barrier. 